The invention relates to a sewing machine provided with a mechanism for producing various stitch patterns by operation of a pattern selecting dial, and more particularly relates to an additional device operated to change the ratio of forward and backward feeding of the fabric with operation of the same pattern selecting dial by utilizing a mechanism for producing stitch patterns including a needle control cam and a feed control cam controlling the feeding movement of the fabric in the forward and backward direction in a predetermined amount.
For stitching a fabric of great elasticity, it is required to feed the fabric in the forward and backward directions repeatedly, generally with the approximate ratio of feeding amounts to 2.5:0.5. Such type of stitches is generally called the "outline stitches". However, in the conventional sewing machines, a feed control cam is generally designed to provide the feeding ratio of amount 2:1 in the forward and backward directions to produce the normally stitched patterns.